diff --git a/src/Trait.ts b/src/Trait.ts
index 6018376..76228c6 100644
--- a/src/Trait.ts
+++ b/src/Trait.ts
@@ -1,5 +1,5 @@
 import { Fn, Pipe, Tuples } from "hotscript"
-import { AbstractClass, Class, Opaque } from "type-fest"
+import { AbstractClass, Class, Opaque, UnwrapOpaque } from "type-fest"
 import { AbstractTag, TraitExpression, emptyTraitExpression } from "."
 import { ExtendFn, SimplifyFn, StaticMembers, StaticMembersFn } from "./util"
 
@@ -16,14 +16,14 @@ export type AddAbstractToImplClass<
 )
 
 export type RemoveAbstractFromImplClass<
-    ImplClassWithAbstract extends Class<Abstract, []>,
+    ImplClassWithAbstract extends Opaque<Class<Abstract, []>, TraitApplierSuperTag>,
     Abstract              extends {},
 > = (
     Class<
         Omit<InstanceType<ImplClassWithAbstract>, keyof Abstract>,
         ConstructorParameters<ImplClassWithAbstract>
     > &
-    StaticMembers<ImplClassWithAbstract>
+    UnwrapOpaque<StaticMembers<ImplClassWithAbstract>>
 )
 
 
@@ -138,12 +138,10 @@ export type TraitApplierSuperTag = "@thilawyn/traitify-ts/TraitApplierSuper"
 
 export function trait<
     Abstract              extends {},
-    ImplClassWithAbstract extends Class<Abstract, []>,
+    ImplClassWithAbstract extends Opaque<Class<Abstract, []>, TraitApplierSuperTag>,
 >(
-    abstract: Opaque<Abstract, AbstractTag>,
-    apply: (Super: Opaque<AbstractClass<Abstract>, TraitApplierSuperTag>) => (
-        Opaque<ImplClassWithAbstract, TraitApplierSuperTag>
-    ),
+    abstract:  Opaque<Abstract, AbstractTag>,
+    apply:     (Super: Opaque<AbstractClass<Abstract>, TraitApplierSuperTag>) => ImplClassWithAbstract,
 ) {
     return new Trait(
         emptyTraitExpression,
diff --git a/src/TraitExpression.ts b/src/TraitExpression.ts
index 9bbdbb2..cd58e47 100644
--- a/src/TraitExpression.ts
+++ b/src/TraitExpression.ts
@@ -12,9 +12,9 @@ import { ExtendFn, SimplifyFn, StaticMembersFn } from "./util"
 
 
 export class TraitExpression<
-    Superclass extends AbstractClass<{}>,
-    OwnTraits  extends Trait<any, any, any>[],
-    AllTraits  extends Trait<any, any, any>[],
+    Superclass      extends AbstractClass<{}>,
+    const OwnTraits extends Trait<any, any, any>[],
+    const AllTraits extends Trait<any, any, any>[],
 > {
     constructor(
         readonly superclass:  Superclass,
@@ -51,13 +51,13 @@ export class TraitExpression<
     }
 
     subtrait<
-        SubtraitAbstract              extends Implements<typeof this>,
-        SubtraitImplClassWithAbstract extends Class<SubtraitAbstract, []>,
+        This                          extends TraitExpression<typeof TraitExpression.NullSuperclass, any, any>,
+        SubtraitAbstract              extends Implements<This>,
+        SubtraitImplClassWithAbstract extends Opaque<Class<SubtraitAbstract, []>, TraitApplierSuperTag>,
     >(
-        abstract: (expression: typeof this) => Opaque<SubtraitAbstract, AbstractTag>,
-        apply: (Super: Opaque<AbstractClass<SubtraitAbstract>, TraitApplierSuperTag>) => (
-            Opaque<SubtraitImplClassWithAbstract, TraitApplierSuperTag>
-        ),
+        this:      This,
+        abstract:  (expression: This) => Opaque<SubtraitAbstract, AbstractTag>,
+        apply:     (Super: Opaque<AbstractClass<SubtraitAbstract>, TraitApplierSuperTag>) => SubtraitImplClassWithAbstract,
     ) {
         return new Trait(
             this,
@@ -99,11 +99,7 @@ export namespace TraitExpression {
     }
 }
 
-export const emptyTraitExpression = new TraitExpression(
-    TraitExpression.NullSuperclass,
-    [] as const,
-    [] as const,
-)
+export const emptyTraitExpression = new TraitExpression(TraitExpression.NullSuperclass, [], [])
 
 
 export type Implements<Exp extends TraitExpression<any, any, any>> = (
diff --git a/src/TraitExpressionBuilder.ts b/src/TraitExpressionBuilder.ts
index a4b5b67..fc7c04e 100644
--- a/src/TraitExpressionBuilder.ts
+++ b/src/TraitExpressionBuilder.ts
@@ -66,11 +66,11 @@ type BuildTraitExpression<
 
 
 class TraitExpressionBuilder<
-    Super     extends AbstractClass<{}>,
-    OwnTraits extends Trait<any, any, any>[],
-    AllTraits extends Trait<any, any, any>[],
+    Superclass      extends AbstractClass<{}>,
+    const OwnTraits extends Trait<any, any, any>[],
+    const AllTraits extends Trait<any, any, any>[],
 > {
-    constructor(private expression: TraitExpression<Super, OwnTraits, AllTraits>) {}
+    constructor(private expression: TraitExpression<Superclass, OwnTraits, AllTraits>) {}
 
     extends<
         Super extends AbstractClass<any>
@@ -87,25 +87,25 @@ class TraitExpressionBuilder<
     }
 
     expresses<
-        Traits extends Trait<any, any, any>[]
+        const Traits extends Trait<any, any, any>[]
     >(
         ...traits: Traits
     ): TraitExpressionBuilder<
-        Super,
+        Superclass,
         [...OwnTraits, ...Traits],
         [...AllTraits, ...SpreadSupertraits<Traits>]
     > {
         return new TraitExpressionBuilder(
             new TraitExpression(
                 this.expression.superclass,
-                [...this.expression.ownTraits, ...traits] as const,
-                [...this.expression.allTraits, ...this.spreadSupertraits(traits)] as const,
+                [...this.expression.ownTraits, ...traits],
+                [...this.expression.allTraits, ...this.spreadSupertraits(traits)],
             )
-        ) as any
+        )
     }
 
     private spreadSupertraits<
-        Traits extends Trait<
+        const Traits extends Trait<
             TraitExpression<any, any, Trait<any, any, any>[]>,
             any,
             any
@@ -120,7 +120,7 @@ class TraitExpressionBuilder<
     }
 
     build() {
-        return this.expression as BuildTraitExpression<Super, OwnTraits, AllTraits>
+        return this.expression as BuildTraitExpression<Superclass, OwnTraits, AllTraits>
     }
 
     then<V>(fn: (expression: ReturnType<typeof this.build>) => V): V {
diff --git a/src/lib.ts b/src/lib.ts
index 9c96c68..9fc1b8f 100644
--- a/src/lib.ts
+++ b/src/lib.ts
@@ -1,3 +1,8 @@
 export {
-    AbstractTag, Implements, TraitApplierSuperTag, abstract, expression, trait, type Trait, type TraitExpression
+    Implements,
+    abstract,
+    expression,
+    trait,
+    type Trait,
+    type TraitExpression,
 } from "."
diff --git a/src/tests.ts b/src/tests.ts
index f8bede5..dd89c0e 100644
--- a/src/tests.ts
+++ b/src/tests.ts
@@ -1,17 +1,18 @@
-import { Simplify } from "type-fest"
 import { Implements, Trait, abstract, expression, trait } from "."
-import { Pipe } from "hotscript"
 
 
 const PrintsHelloOnNew = trait(
     abstract(),
     Super => class PrintsHelloOnNew extends Super {
+        static readonly isPrintsHelloOnNew = true
+
         constructor(...args: any[]) {
             super(...args)
             console.log("Hello!")
         }
     },
 )
+type PrintsHelloOnNewClass = Trait.Class<typeof PrintsHelloOnNew>
 
 const Identifiable = <ID>() => trait(
     abstract<{ readonly id: ID }>(),
@@ -34,6 +35,7 @@ const StatefulSubscription = trait(
 
     Super => class StatefulSubscription extends Super {},
 )
+type StatefulSubscriptionClass = Trait.Class<typeof StatefulSubscription>
 
 const ActiveStatefulSubscription = expression
     .expresses(StatefulSubscription)
@@ -51,7 +53,7 @@ const ActiveStatefulSubscription = expression
         Super => class ActiveStatefulSubscription extends Super {},
     )
 
-type T = Trait.Instance<typeof ActiveStatefulSubscription>
+// type T = Trait.Instance<typeof ActiveStatefulSubscription>
 
 
 class TestSuperclass {